BACKGROUND: In 2014, the infant mortality rate in the United States (US) was 5.6 deaths per 1,000 live births; one of the highest in the developed world. Within the US, Missouri ranks 32nd out of 50 states with an infant mortality rate of 6.6 deaths per 1,000 live births. There are numerous factors that contribute to infant mortality including adverse birth outcomes, as well as sociodemographic variables. In many states, perinatal regionalization systems have been implemented, either formally or informally, to provide high quality, cost-effective, coordinated care to mothers and infants to improve birth outcomes and reduce infant mortality. There is a need to better understand the relationship between systems of perinatal regionalization and other factors, such as adequacy of prenatal care and insurance status, in prevention of adverse birth outcomes.
METHODS: A retrospective cohort of 2010-2012 Missouri birth certificate data, composed of singleton infants born in hospitals to Missouri residents, was analyzed to assess neonatal mortality, preterm birth, and very low birth weight (VLBW) delivery by birthing hospital level. Adequacy of prenatal care and insurance status were considered as effect modifiers in the relationship between hospital level and the three adverse birth outcomes of interest. Relationships were assessed using logistic regression, in which both crude and adjusted models were built.
RESULTS: Adequacy of prenatal care was an effect modifier in the relationship between hospital level and all outcomes; insurance status was an effect modifier in the relationship between hospital level and VLBW delivery. Those with adequate prenatal care had significantly increased odds of having a baby with VLBW at a level 3 hospital in reference to non-level 3 hospitals (aOR=3.70, 95% CI: 3.21,4.25), and those with inadequate prenatal care were also had significantly increased odds of having a baby with VLBW at level 3 in reference with non-level 3 hospitals (aOR=1.98, 95% CI: 1.54,2.54). Those with Medicaid had significantly decreased odds of having a baby with VLBW at a level 3 hospital compared to those with private insurance delivering at level 3 hospitals in reference to a non-level 3 hospitals (OR=2.25, 95% CI: 1.96,2.58 and OR=4.53, 95% CI: 3.73,5.50, respectively).
CONCLUSIONS: Perinatal regionalization has previously been shown to decrease adverse neonatal outcomes. This study indicates that other factors, including insurance status and adequacy of prenatal care modify the relationship between VLBW and birthing hospital level. Future studies could explore how additional access to care factors, including geographic distance, may influence these relationships.